The lack of enough intake to get up to temperature is a very good sign that you have solved the potential leaky door issue. This is going to be one sweet UDS once you add the extra intakes.
Jim - Another transplanted Texan
Former KCBS CBJ
Large and Medium Big Green Eggs , Black 18.5" WSM, Blue Weber Performer - Stainless, Green Weber OTG Kettle , Brinkmann SnP Pro, and a Stainless UDS. One retired Portable Kitchen grill.
Red Thermapen, Maverick ET-73, EdgePro Apex Sharpener.
Avatar is the original 1951 Weber Kettle